The concept of entropy in histopathological diagnosis and targeted therapy

Background Targeted therapy has been developed to apply individual patient – specific drug regimes that are based upon specific bio-chemical intra-cellular pathways and usually related to cellular proliferation or apoptosis. Entropy Definition and Concept Entropy is considered to be a physical entity similar to space and time. It quantifies the distribution of events and transport mechanisms in relation to the macrosystem for thermodynamic, chemical and biological processes which are analyzed by statistics, communication and information methods. It amounts the distance of a gross (macro) system from its final stage in heat theory; in biology the entropy flow measures its dynamics (distance from its environment) through the surface of an open macrosystem, for example of a society, an individual, an organ, a gene, cell, and others. A derivative of entropy is the so-called structural entropy that measures the distance of internal (enclosed) microstates in the macrosystem. It can be computed by quantification of internal (vascular) and external (outer) surfaces of solid tumors, and their proliferation. Entropy and targeted Therapy The most frequently investigated pathways include onco and suppressor genes that display pathways with cellular surface receptors such as the epidermal growth factor receptor (EGFR), and others. The presence and signalling intensity of EFGR in a set of malignant tumors can be considered as microstate in a large compartment of the whole cancer (macrosystem). Thus entropy and structural entropy can measure and classify the internal dynamic structure of the investigated cancer and can be associated to the therapy response and patient’s survival. Results The concept of entropy and structural entropy has been tested and applied on several cancer cell types including primary lung cancer and pulmonary metastases of colon cancer. The patients’ survival rates were closely associated with the corresponding entropies and entropy flows. These tests have been based upon visualization of proliferation (Ki-67). The extension of this entropy concept to be applied in targeted therapy of breast and lung cancer is under investigation. Conclusion The concept of conventional and structural entropy is a promising tool in search for understanding biological structures and their related functions, for improved analysis of microstate dynamics in malignant tumors, and can serve for refinement of targeted therapy.